Halogenated tetracycline derivatives and processes for their preparation



United States Patent C) 3,043,875 HALOGENATED TETRACYCLINE DERIVATIVES AND PROCESSES FOR THEIR PREPARATION John J. Beereboom, Waterford, Hans H. Rennhard, Lyme, and Charles R. Stephens, Jr., Niantic, Conn, assignors to Chas. Pfizer & (30., Inc., New York, N.Y., a corporation of Delaware N Drawing. Filed Feb. 8, 1960, Ser. No. 7,085 21 Claims. (Cl. 260-559) OH H .0-

Among the biologically active members of this group are those containing the following substituent groups:

Substituents Common Name tetracycline. -oxytetracycline. 7-chlorotetracycline.

4 N(GH3)z, e-on, 6-011 12a-OH 4-month, s-on, G-OH, 6-011 12a-OH 4-N(CH3)2, 5-0H, G-OHa, 12a-OH fi-deolzgy-fi-oxytetracyc me. E-OH, 6-0113, l2a-OH, fi-OH -desdimethylaminofi-oxytetracycline. 4-N(CHs)2, 6-OH3, 12a-OH G-deoxytetracycline. 4-N (011 1231-0H 6-deoxy-6-dernethyltetracycline. 4-N(OHa)2, 6-011, 6-CH 7-Br, 12a-OH 7-bromotetracycline. 4-N(OH3), G-OH, 7-01, 12a-0H 6-demethyl-7- chlortetracycline. G-OH, 6-0113, 12a-OH 4-desdimethylamino tetracycline. 6-0H, 6-0113, 7-01, 12a-OH t-desdimethylamino- 7-chlortetracycline. 4-N(0H )2, 6OH, 12a-OH 6 d1e methyltetracy- 0 me. 12a-OH. 6-de0xy-6-demethyl- 4-desdimethylaminotetracycline.

The present new compounds are Ila-halogenated acidstable tetracyclines having at least one hydrogen in the 6-position. It is also intended to include salts of the present new compounds with both acids and bases, and in particular, mineral acid salts and alkali and alkaline earth metal salts. Acid stable tetracyclines include 6-deoxyand 6-deoxy-6-demethyltetracyclines as well as the corresponding 4-desdimethylamino compounds. 01: course, it is Well known that the parent tetracycline, e.g. tetracycline, oxytetracycline and chlortetracycline, lack acidstability since they are readily converted to the corresponding anhydrotetracyclines in the presence of acid.

3,043,875 Patented July 10, 1962 The present new compounds may be represented by the following formulae:

Z R R1 R2 R is selected from the group consisting of H and CH R is selected from the group consisting of H and, when R is CH OH;

R is selected from the group consisting of H and X and Y are halogen;

Z is selected from the group consisting of H and halogen;

and

B is selected from the group consistingof bromo, chloro and iodo.

[The 1 1a-monohalotetracyclines represented by the formula:

wherein X, R, R and R as above described are'useful as intermediates for further substitution of the tetracycline nucleus, particularly in the D-ring. Where R is hydrogen further substitution reactions may occur in the rings A and D.

It is known that the Ila-position of the tetracycline nucleus is quite reactive and, when substitution reactions are to be effected elsewhere in tetracycline nucleus, it is desirable to block the Ila-position, for example by the etherification of the enolic hydroxy group at the 11'- or l2-position or transformation thereof to a so-called enamine as described in copending application Serial Number 847,867, filed October 22, 1959. The essential feature of the aforementioned ether and enamine derivatives is that the active hydrocarbon atom associated with the 11-., 11a, and 12-positions is removed. The present new 11ahalotetracyclines may be used in the same way as the above mentioned ethers and enamines, with the advantages that the Ila-halo group is readily introduced into the tetracycline molecule and readily removed by simple procedures as hereinafter described. For example, the present lla-monohalotetracyclines serve as intermediates for the production of corresponding 7,1la-dihalotetracyclines and 7,9,1la-trihalotetracyclines. They may also be used as intermediates for the production of 7-substituted azo tetracycline compounds described in copending application Serial Number 847,867, filed October. 22, 1959..

Those in which R is hydrogen are also useful as intermediates in the preparation of tetracyclines which are further substituted in the A ring. After formation of the desired substitution product, the Ila-halo blocking group may be readily-removed as hereinafter described. The lla-monohalotetracyclines have reduced in vitro antibacterial activity as compared to the parent tetracyclines though good in vivo activity is frequently noted. This property renders the compounds particularly valuable in human oral therapy especially in patients susceptible to diarrhea and other intestinal disorders since unabsorbed antibiotic is relatively inert in the lower bowel.

The biological activities of these substances measured by the standard serial dilution are tabulated below.

IN 'VITRO ANTIBACTERIAL ACTIVITIES A11a-chloro-6-deoxy-S-dernethyltetracycline B11a-bromo-G-deoxy-Gdemethyltetracycline -11a-fluoro-6-deoxy-6-demethyltetracycline D-6-deoxy-6-demethyltetracycline A I B O D Micrococcus pyogenes var. aureus 6.3 3.12 6. 3 0. 19 Streptococcus pyogeues 3.12 1. 56 6. 3 0.19 Streptococcus faecalz's 6. 3 6. 3 12.5 O. 19 Diplococcus pneumo'n 3. 12 1. 56 12. 0. 19 Eryaipelothriz rhusiopathiae. 6. 3 3. 12 6. 3 0.19 C'orynebacterium diphtheriae 12.5 6. 3 12. 5 0.02 Listeria mouocz/togeues 3. 12 3. 12 12. 5 0. 19 Bacillus'subtilis 0. 39 0. 78 3. 12 0. 04 Lactobacillus casei 12.5 12.5 12. 5 0. 19 Bacterium ammoniagenes 3. 12 1. 56 12.6 0. 19 A'erobacter aerogeaes; 25.0 6. 3' 50 1. 56 Escherichia coli 12.5 r 6. 3 12.5 1. 56 Proteus vulgarz's... 100. 0. 100 100 100 Pseudomonas aerug 0.! 100. 0 100 100 100 Salmonella typhosan 25. 0 6. 3 100 1.56 Salmonella pullorum 12.5 6. 3 25 0. 78 Klebsiella pneumoniae. 12. 5 6. 3 g 50 1. 56 Neisseria gouorrhoeaen 3.12 .1. 56 12.5 0. 19 Haemophilus influenzae 1. 56 0. 78 6. 3 0.09 Shigella sonrzei 12.5 12.5 50 1. 56 Erwiuia amylovorm 100 12.5 100 Phyto ytumef 3. 12 Brucetla brouchiseptica 0.78 0.78 0. 19 Malleomi ces maZIei 0.3 6. 3 .25 Vibrio comma 0.78 0.78 3.12 Pasteureila multoczdm- 3.12 3. 12 12.5 0.39 Mycobacterium 607 1. 56 3. 12 100 Mycobacterium ber0lme'nse 0.78 1. 56 100 Candida albicans 100 100 100 Pityrosporum ovate 12078 100 100 100 Antibiotic resistant strains of M icrococcus pyogenes var. aureua l The MIC of tetracycline against Micrococcus pyogenes var. aureus is 0 39.

'2 Resistant to tetracycline at a concentration of 100 meg/m1.

Resistant'to tetracycline at a concentration of below 50 meg/ml.

When these in vitrotests were repeated in the presence of human serum, similar results were obtaineddernonstrating that the present antibiotic compounds are not deactivated in theblood. When these compounds were tested in vivo through both the oral and parenteral route in --mice, they showed activity comparable to tetracycline against infection produced with tetracycline sensitive rnicroorganisms,e.g. Micrococcus pyogenes var. aureus. For example, the PD (PD=protective dose) for 11achloro-6-deoxy-6-demethy1tetracycline against an infection produced with M icrOcoccus pyrogenes var. aureus, is 5.5 nag/kg. (orally) and 1.3 mg./kg. (parenterally) while the corresponding-PD for'tetracycline are 5.3 and 0.68 mgjkg. respectively. The high order of in vivo activity of the present lla-halotetracyclines is certainly unexpected in view of the hereindescribed in vitro activities.

The present new compounds may be formulated into various compositions analogous to the parent compounds. They are useful in therapy particularly because of the lack of appreciable activity in the intestines while providing systemic protection against disease causing microorganisms. They are also useful therapeutically in feeds or as growth stimulants, in veterinary practice, and in agriculture.

For human therapy, the usual oral dosage of the present lla-halotetracyclines is from about 0.4 to about 2 g. per day for the average adult. The products are formulated into capsules or tablets containing from 25 to 250 mg. of antibiotic on an activity basis. Suspensions or solutions in various vehicles are prepared having concentrations ranging from 5 to 125 mg./ml. For parenteral administration intramuscularly or intravenously, the daily dose is reduced to about 0.1 to 1.0 g. Intramuscular formulations comprise solutions of the antibiotic at concentrations ranging from 50 to 100 mg./ml. Intravenous administration is by means of isotonic solutions having antibiotic concentration of about 10 mg./ml. Both types of parenteral product are conveniently distributed as solid compositions for reconstitution. In all instances, of course, the attending physician will indicate the dosage to fit the needs of a particular patient. For children, smaller doses are generally used.

The 7,l'1a-dihalotetracyclines represented by the formula:

X R R R:

A/\ I OH OONH I H X II H OH 0 0 wherein X, R, R and R as described above are useful as intermediates for the preparation of corresponding 7-halotetracyclines described in copending application Serial Number 847,867, filed October 22, 1959, and also for the preparation of 9-substituted tetracycline compounds also described in the same copending application, by procedures involving the removal'of halogen, as hereinafter described, .afterintroduction of the desired substituent. The 7,9,1la-trihalodesdimethylaminotetracyclines are intermediates for the production of corresented by the following formulae:

R R l l I 7 H I [I on 0 OH Y employed, the principal product is the corresponding 11ahalo (Cl, Br, or I) tetracycline. When Z is hydrogen in Formula IV slight excesses of halogenating agent, up to mole-percent, may be also used in preparing the 11amonohalo compounds. Larger excesses of halogenating agent may result in reduction of the yield of the desired monohalo product. Of course when Z is halogen, large excess of halogenating agent may be used but provide no appreciable advantage.

When two molar equivalents of halogenating agent are used with a compound of Formula IV in which Z is hydrogen, the corresponding 7,11a-d-ihalo-tetracycline is obtained. For best results in this reaction an acid catalyst is preferred in the reaction mixture for D-ring substitution. When the halogenating agent is a chlorinating agent, the corresponding 7,1,1 a-dichlorotetracycline is obtained; when a brominating or iodinating agent, the corresponding 7-bromoor 7-iodotetracycline is obtained, apparently through disproportionation of the mobile llabromo or iodo, or through interact-ion with the reaction medium. The product may also contain the 7,11adibromo (or diiodo) compound. 7

When the starting compound is an Ila-halo (Cl, F, I or Br) tetracycline only an equimolar amount of halogenating agent is required although excess may be used with no appreciable advantage. When the Ila-halogen is bromine or iodine, a 7-monohalotetracycline is obtained in the presence of an acid catalyst, which appears to be preferable for production of substantial amount of 7-substituted product. When the Ila-halogen is chlorine or fluorine, the latter prepared by a procedure hereinafter described, the products obtained are 7-halo-llachloroor fluorotetracycline.

When the startin com ound is de d th 1 g p a S lme y ammo 35 4.2 buffer as the immobile phase. The halotetracycl nes tetracycline, the acid catalyst does not appear-to be as desirable as in the case of the tetracyclines. Excellent results are obtained without acid catalysts by merely contacting the starting desdimethylaminotetracycline with the halogenating agent in a reaction-inert solvent. The molar ratio of halogenating agent to statring compound determines the product obtained. With an equimolar ratio, there is obtained the Ila-halo compound; with a 2:1 molar ratio, the 7,11a-dihalo compound and with a 3:1 molar ratio, the 7,9,11a-trihalo compound.

It is surprising that the desdimethylaminotetracyolines yields a trihalo product under comparatively mild conditions. The formation of 7,9,1la-trihalotetracyclines require more selective halogenation conditions for high yields, though small amounts of these trihalo compounds are'frequently formed as by-products along with 9,11adihalotetracyclines in the hereindescribed method of producing 7,1la-dihalotetracyclines.

Suitable halogenating agents for the present process include bromine; chlorine; iodochloride; iodobromide; N-chloro-, N-iodo-, and N-bromo lower alkanoic acid amide, e.g. N-chlor-, and N-bromacetarnide; hydrocarbon dicarboxylic acid imides, e.g. N-chloro-, N-bromoand I N-iodosuccinimide, phthalimide, and the like and N- lower-alkanoyl anilines e.g. N-bromoacetanilide, propionanilide and the like; 3-chloro 3-bromo-, 3,5-dichloro and 3,5-dibromo-5,5-dimethyl-hydantoin; pyridiniumperbromide and perchloride hydrohalides, e.g. pyridinium perbromide hydrobromide; pyridinium perchloride hydrochloride; and lower alkyl hypochlorites, e.g. tertiary butylhypochlorite. It is obvious that, in general, any-halogenating agent commonly employed in the art is operable, but the above are preferred.

By reaction-inert solvents as employed herein is meant a solvent which, under the conditions of the reaction, does not react in an undesired manner with either starting compounds or final products. A minimum of .laboratory experimentation will permit the'selection of suitable solvents for the present process. Exemplary of 25 genation.

3O solvent systems.

. 6 such solvents are dioxane, acetic acid, tetrahydrofuran, carbontetrachloride, chloroform, methyl ether of diethylene glycol (diglyme), and the methyl ether of ethylene glycol (monoglyme). Water may also be used as solvent 5 for the present process, particularly when a mineral acid is used as catalyst for D ring substitution reaction. Of course, when a chlorinating agent is used because of the stability of the Ila-chlorine, an acid may be present even in monochlorinating. Particularly effective solvents for 10 chlorination are trihaloacetic acids, e.g. trifluoacetic and trichl-oroacetic acids, which serve both as solvent for the reaction and catalyst for the D-ring substitution.

In the foregoing, reference is made to an acid catalyst for D ring substitution reactions. A variety of such acids may be employed in the present process. These include and organic carboxylic acids and in particular halosubstituted alkanoic acids, e.g. trifluoro and trichloro lower alkanoic acids, preferably trifluorand trichloracetic acid. A minimum of routine laboratory experimentation will enable the selection of suitable acids for D ring halo- For example, small scale reactions may be carried out with the tetracycline compound, the halogenating agent, and the selected acid in an inert solvent. Paper chromatography may then be used to detect the presence of D-ring halogenated tetracycline using known Exemplary of such solventsystems are the following: ethyl acetate saturated with water as the mobile phase and MacIlvaines pH 3.5 bufieras the immobile phase; and 20:3 toluene:pyridine saturated with pH 4.2 buffer as the mobile phase and MacIlvaines pH show a differential mobility and can be distinguished from starting compound, the behavior of which may be predetermined in the same solvent system.

The acid catalyst may be used in trace amounts but 40 it is generally preferred to employ excess to ensure rapid Reaction temperature does not appear to be critical in the present processes since the reaction is initiated even at room temperature and at lower temperatures on contacting the reagents. The use of higher temperatures merely serves to ensure completeness of the reaction'and shorten the time required. The use of temperatures higher than about 100 C. provides 'no appreciable advantage and should be avoided since it may result 'in decreased yield of the desired product. At room temperature, the reaction is complete in as little as 5 to 30 minutes. Of course, the reaction time will depend on the amounts of materials employed, large-scale preparations requiring longer periods than laboratory scale.

After the reaction is complete, the products are obtamed by conventional procedures of isolation. One such procedure involves the dilution of the reaction mixture with a non-solvent, e.g. ether, after which the separated 'product is collected. The products as obtained are usually of sufficient purity to be used for further substitution 7 reactions but, if desired, they may be recrystallized from duction of substantial amounts of the desired Ila-fluorotetracycline, it is necessary to carry out the reaction in 'thepresence of a base. While, a variety of bases may be used,'it is preferred to use alkali metal lower alkoxides and alkali and alkaline earth metal hydroxides, carbonates, and bicarbonates as catalyst. Other bases, such as organic 3 aminesjeg. trialkylamines such as triethylamine, nitrogen heterocyclics such as-pyridine and the like are operable but offer no advantage over the more economical 'alkoxides. metal lower alkoxides such as sodium-methoxide, potassium ethoxide and lithium'propoxide.

I tis generally advisable to utilize at least one equivflent of base per mole of starting compound. Lesser amounts of course may be used but lower product yields may be "realized in so doing. .The use of more than an equivalent base is optional since though operable, it provides no appreciable advantage.

7 Reaction temperature does not appear to be critical since the reaction is operable overa wide range of temperature. However, it is recommended that temperatures higher than 30 C. be avoided since appreciable side reactions mayoccur resulting in reduced product yield. The preferred reaction temperature is from about -10 to aboutl0 C. Theuse of lower temperatures, while operable, usually-necessitates prolonged reaction periods and I thus is not preferred.

. The fiuorinating agent is gaseousunder ordinary conditions but at low temperature may be maintained in the liquid state. The perchloryl fluoride may be introduced into the reaction mixture portionwise or all at once in either physical state. It isconveniently utilized in the gaseous form and-,- as such maybe continuously bubbled through the reaction mixture until monofluorination is complete. Alternatively the reaction mixture may be saturated with the gas and the reaction simply allowed to proceed. A further method involves introduction of the gas under pressure. For this procedure, conventional pressure vessels are useful as reaction containers.

7 Althoughat leasta molar equivalent of perchloryl fluorideis required permole of substrate, it is usually more convenient to use excess reagent, particularly when the I gaseous form is employed.

Reaction-inert solvents for the present fluorin-ation process are readily determinable by routine laboratory experimentation. Of course, theselected solvent should dissolvethe tetracyclinestarting compound. Such solvents include those described above. Preferred solvents for the presentprocess are lower alkanols, e.g., methanol,

ethanol and propanols, since their use gives best results.

In the foregoing, mention is made of the removal of the Ila-halogen from the final products. Conventional procedures such as treatment of the lla-halotetracyclines (a) With'dilute aqueous hydriodic acid,

(b) With zinc metal in the presence of a proton donor, such as acetic acid,

(0) vIn the case of ll-abromo and lla-iodo compounds, by boiling the product with a solvent capable of reacting with bromine or iodine (acetone, methanol, etc.),

(d) Alternatively treatment with sodium iodide in organic solvent, followed by treatment of the resultant iodo compound with metallic zinc, and

(e) Treatment with metal sulfites and hydrosulfites, particularly the alkali metal (Na, K, Li) salts are useful. Sulfites do not appear to be effective in removing llachloro or throw, but readily reduce oif lla bromoor iodo. Hydrosulfites, on the other hand, are particularly efiective in removing all 11a-halogens. The reaction appears to be instantaneous when carried out in water, and for this reason this solvent is preferred; However, other solvents, e.g. alkanols may be employed. The reaction is rapidly completed at room temperature.

The procedure under (d) is found to be very inetlicient .in that the first reaction appears to beat best quite incom plete. It has been surprisingly found that lla-halotetra- The preferred bases are alkali s cyclines maybe readily dehalogenated by simultaneous treatment ofa compound of the formulae:

Y R R1 0 ONE:

M i (bu wherein R, R Y, X and R are as previously described, and B is fluoro, chloro or bromo; and mineral salts thereof, with zinc and sodium iodide in a reaction-inert organic solvent. Suitable solvents are readily determinable by routine laboratory experimentation and include'solvents for the tetracycline starting compound which are capable of dissolving at least in part, the sodium iodide reagent. Preferred solvents are lower alkanones such as acetone, butano ne and pentanones since their use gives best yields. Theoretically, only equivalent amounts of zins and sodium iodide are required for the present process but it is found advisable to use excesses of same in particular to shorten reaction time and obtain optimum yields. Excesses of up to 1000 mole-percent and higher are successfully used in the present process. Temperature does'not appear to'be oritical'but merely affects the reaction rate. The use of high-temperatures, for example up to the reflux tempera ture of the reaction mixture, merely shortens the reaction time. For example, with the; solvent acetone, the reaction is complete in as little as 30 minutes when the mixture is maintained at reflux temperature.

After the reaction is complete the products are obtained by filtration and concentration of the reaction ture. The products may be further purified by standard procedures, e.g., recrystallization from suitable solvents.

It has also been surprisingly found that the Ila-halogen may be'removed from the dihalotetracyclines of this invention by catalytic hydrogenation. This is indeed unexpected since the 7-halogen is also susceptible to catalytic hydrogenation.

The hydrogenation is carried out by contacting an inert organic solvent solution of the starting dihalotetracycline with hydrogen gas in the'presence of a noble metal catalyst. The hydrogenation. may be carried out at atmos pheric or superatmospheric pressures of hydrogen. It is usually preferred to use from about 1 to about 3 atmospheres of hydrogen gas at temperatures ranging up to 50 'C. Temperatures of from about 25 to about 35 C. appear to give optimum results and arepreferred. The

lower alkanols, tetrahydrofuran, diglyme and monoglyme.

After the reaction is complete, the catalyst is filtered oif and-the product obtained by standard procedures.

6-deoxy and 6-deoxy-6-demethyltetracyclines are described in copending application Serial Number 841,928, filed'September 24, 1959. The G-demethyltetracyclines are described in US. Patent No. 2,878,289. The cone 9 sponding 4-desdimethylaminotetracyclines are described in copending application Serial Number 841,929, filed September 24, 1959.

The herein described 7,9-1la-trihalo-4-desdimethylaminotetracyclines are also of particular value in preparing the new and useful corresponding 7,9-dihalo compounds of the following formula:

i GONHz in which R is selected from the group consisting of H, OH and CH R is selected from the group consisting of H and, when R is CH OH; Y is halogen; and B is selected from the group consisting of bromo, chloro and iodo.

The 7,9-dihalotetracyclines possess surprisingly high activity against disease-causing microorganisms, and particularly against antibiotic-resistant strains of such microorganisms. They are useful for human and animal therapy in the same way as the parent tetracycline antibiotic, the eflicacy of which is well documented in the medical literature. The 7,9-dihalo compounds may 'be used in the acid form or in the form of salts with pharmaceutically acceptable cations, particularly pharmaceutically acceptable alkali; and alkaline earth metal cations. It is specifically intended to include within the purview of this invention the acid and base salts of the present new amphoteric tetracyclines, and the base salts of the present new acidic tetracyclines i.e. the 4-desdimethylamino compounds. In the case of the therapeutically active tetracyclines, salts formed with pharmaceutically aceptable acids and bases are suitable for administration to a host in suitable dosage form. Those salts formed with pharmaceutically unacceptable acids and bases are of value in isolation and purification of the present new tetracyclines and also in the preparation of pharmaceutically acceptable salts.

The following examples are given by way of illustration and are not to be construed as limitations of this invention many variations of which are possible without departing from the scope and spirit thereof.

Example I 11a-CHLOR0-6-DEMETHYL-G-DEOXYTETRACYCLINE separates and is then slurried four times with ether.

Example 11 7,11a-DICHLORO-6-DEMETHYL-G-DEOXYTETRACYCLINE The product of Example I is stirred with 0.8 g. of

'N-chlorosuccinimide in 17 ml. of trifluoracetic acid on a steam bath for thirty minutes. After cooling, the mixture is added dropwise to 500 ml. of stirred ether at C. The hard, oily gum is separated and slurried four times with ether to obtain the product.

The product is also obtained from 6 -deoxy-6-demethyltetracycline by this procedure employing 1.6 g. in lieu of 0.8 of the chlorinating agent.

A sample of the product in 0.01 N-methanolic I-ICl 'shows maxima on ultraviolet absorption analysis at 270 and 358 mp. Infrared analysis is a KBr pellet at a concentration of 1% shows absorption at the following wavelengths: 2.953.45, 3.36, 4.15, 5.73, 5.87, 6.10 (6.40),

is collected by filtration. pulped several times with ether.

1 0 7 Example III 7-BROMO-6-DEOXY-6-DEMETHYLTETRACYCLINE A mixture of 2.5 g. of 6-deoxy-6-demethyltetracycline hydrochloride and 10 ml. of a solution of bromine in acetic acid (1.6 g. of bromine) in 25 ml. of trifluoracetic acid is heated on a steam bath for 5 minutes. The heavy orange precipitate which first forms on mixing the starting reagents slowly dissolves to give a dark green solution. Heavy fuming of the mixture occurs during heating. After cooling, ml. of methanol is added and a negative starch-iodide test indicates that all of the bromine has reacted. The solvent is evaporated in vacuo to give a taffy-like residue which is triturated with dry ether to yield amorphous product which is collected. After 1.5 g. of this product is dissolved in 100 ml. of hot methanol and 20 drops of 48% hydrobromic acid is added. The mixture is evaporated to 75 ml. and cooled. A yellow crystalline solid precipitates giving 1.3 g. of 7-bromo-6- deoxy-G-demethyltetracycline hydrobromide. violet absorption maximum occurs at 268 mp with a broad plateau (maximum) occurring at 343 to 36711111. when this An ultraproduct is dissolved in 0.01 N methanolic HCl. Ultraviolet maxima appear at 243 and 383 m in 0.01 N methanolic NaOH. Infrared absorption maxima occur at 2.99, 3.20, 6.05, 6.25, 6.85, 7.15, 7.40, 7.80, 8.20 and 8.85 (1% dilution in potassium bromide pellet).

This product is also obtained from 11a-bromo-6-deoxy- 6-demethyltetracycline by the same procedure as described in this example.

Example IV 7 -BROMO -6-D1lOXY-5-OXYTETRACYCLINE A mixture of 50 mg. (0.1 mmole) of 6-deoxy-5-oxytetracycline, 0.21 ml. of a solution of 1.6 g. of Br in 10 ml. of acetic acid and 0.5 ml. of trifluoroacetic acid is heated on a steam bath for 5 minutes. The initial heavy orange Example V 11a-FLUOR0-6-DEMETHYL-G-DEOXYTE'BRACYCLINE A suspension of 4.6 g. (10 mmoles) of 6-demethyl-6 deoxytetracycline hydrochloride in 60 ml. of methanol is cooled to 0 C. and nitrogen gas bubbled through. A solution of 20 ml. of a normal solution of sodium methoxide in methanol (20 mmoles) is added and the "mixture saturated with perchloryl fluoride. The mixture is then maintained in a refrigerator for 24 hours during which time the suspension becomes a clear yellow solution which deposits 3.5 g. of cream colored crystals of the product as the chlorate salt; The filtrate yields a second crop of crystals of less pure product.

Ultraviolet analysis shows maxima at 270 and 350 m Example VI lla-HALOGENATION The tetracycline starting compound is dissolved in the selected solvent and an equivalent of chlorinating, bromi- -'nating or iodinating agent is added to the resulting mixture. After stirring at room temperature for A to 24 hours, the mixture is added dropwise to a non-solvent, usually ether, at about 0 C. The product separates and It desired, the product is re- .This procedure is used for the preparation of the following lla-halotetracyclines from corresponding tetracyclines from corresponding tetracyclines:

1 1a-bromo-6-deoxy-6-demethyltetracycline '11a-bromo-6-deoxytetracycline 1 la-bromo-6-deoxy-5-oxytetracycline 1'1a-iodo+6-deoxy-G-demethyltetracycline I l la-iodo-fi-deoxytetracycline 1 la-chloro 6-deoxy-4-desdimethylaminotetracycline 11a 7 bromo 6 deoxy-6-demethy-l-4-desdimethylaminotetracycline j7-chloro-1 1 a-bromo-6-deoxy- 6-demethyltetracycline fl-fluoro-l la-chloro-6 deoxytetracycline 7-brorn'o-11a chloro-6-deoxytetracycline L7,1 1a dibromo-6-deoxyrG'demethyltetracycline 7,1 1a=dibromo-6-deoxytetracycline Halogenating agents useful in this regard include: chlo- -rine, bromine,-iodochloride, 'iodobromide, N-bromosuc- Example VII lla-FLUORINATION Thetetracycline compound in the selected solvent containing a basic catalyst is treated 'with perchloryl fluoride at atmospheric or super-atmosphericpressure. For the latter, a conventional pressure Vessel is suitable. The mixture ispreferably allowed to stand at a temperature between --10'and l C., usually at 0 to C. At the :end of about a 24 hour period, the product usually precipitatesp In some cases, it may be necessary to effect precipitation by concentration and/or the addition of a non-solvent such as ether. 7

Using this procedure, .the following lla-fluorotetracyclines are prepared from corresponding starting compounds: r w

1'1a-fluoro 6r-deoxytetracycline lla fiuoro 4 desdimethylamino 6 'deoxy 6 demethyltetracycline .1 1a-fluoro-6-deoxy-5-oxytetracycline 7-chloro- 1 1a-fluoro-6-deoxytetr acycline 7-bromo-l 1a-fluoro-6-deoxy 6-demethyltetracycline 4 t 1 1a-fluoro-4-desdimethylamino-6-deoxytetracycline Suitable reaction solvents are preferably lower alkanols,

e.g. methanol'and ethanol. Additional solvents are dioxa'ne, water,-tetrahydrofuran, diglyme and monoglyme.

Basiccatalysts include sodium methoxide, potassium ethoxide, lithium propoxide, sodium hydroxide, lithium hydroxide, potassium carbonate and sodium bicarbonate and carbonate. I

In fluorinating 4 desdimethylaminotetracyclines,the reaction is preferably carried out in lower alkanols and the product precipitated by water addition after about 1020 minutes reaction time. I

Example VIII 7-HALOGENATION Method] A. --The tetracycline starting compound in suitable solvents containing an acid catalyst is heated on a steam bath with atleast two equivalents of halogenating agent for 30 minutes. After cooling the mixture is added dropwise to stirred ether at 0 'C. The product iseparates, is collected and then slurried several times with ether. 1

When the 7 -halogen is bromo or iodo, the product may contain minor amounts of the corresponding 7,11a-di- "halo'tetracycline. It may be purified by heating in acetone or methanol (serving as halogen acceptors) or alternatively a solution of a mineral acid (hydrohalic, perchloric or sulfuric) in acetone or methanol, followed by evaporation and crystallization. I

Method B.-To thella-halotetracycline starting compound in suitable solvent containing an acid catalyst is added at least one equivalent of. halogenating agent and the mixture allowed to stand at room temperature for about three to four hours, after which the product iscollected by the usual procedure (e.g. Method A).

When the lla-halogen is bromo or iodo, the final 7- halotetracycline may also contain minor amounts of 7 halo-lla-bromo or iodobompound. Purification of the product may be carried out as in Method A. Suitable solvents for both Methods A and B include trifiuoracetic, trichloracetic, 48% aqueous hydrobromic acid, sulfuric acid, hydrochloric acid, and phosphoric acid (which may act as catalyst as well as solvent) as'wellias dioxane, tetrahydrofuran, diglyme, monoglyme, carbon tetrachloride and chloroform. Acid catalysts include the aforementioned as well as boron trifluoride, stannicchlorideand zinc chloride.

Under the procedure of Method A, the following 7- halotetracyclines are prepared from corresponding starting compounds using the halogenating agents described in Example VII. 7

7,1 1a-dichloro 6-deoxytetracycline 7 bromo 6-deoxytetracycline 7-iodo-6 deoxytetracycline 7 -bromo-6-deoxy-6-demethyltetracycline 7,11a-dichloro-6-deoxy-S-oxytetracycline Using the procedure of Method B, the following 7- halotetracyclines are prepared from corresponding llahalo compounds using the'halogenating agents described in Example VII.

'7-cbloro-6-deoxy-6-demethyltetracycline (from the corresponding lla-bromo compound) 7,11a-dichloro-6-deoxy-'6-demethyltetracycline (from the corresponding lla-chloro compound) '7-bromo-6-deoxytetracycline (from the corresponding 11abromo compound) 7-iodo-6-deoxytetracycline (from the corresponding 11aio'do compound) 7,1 la-dichloro-6-denxyd-oxytetracycline 7-iodo- 1 1 a-chlo'ro-6-deoxytetracycline 7-bromo-1 1a-chloro-6-deoxytetracycline 7 -ch1oro-1 1a-fluoro-6-deoxy-6-demethyltetracycline Example IX HYDROGENATION Ila-HALOTETRACYCLINES 5% palladium oncarbon. The mixture is treated at a pressure of 3 atmospheres of hydrogen, gas and a tern- .perature of 32 C. The hydrogenation stops after .22

minutes and the mixture is filtered and the resulting light red solution evaporated to dryness at reducedpressure. The residue is slurried in 25 ml. of-ether, filtered and .dried to obtain 0.92 g. of yellow solid, 7-chloro-6-deoxy- 6-demethyltetracycline.-

Using this general procedure, the aforementonedllahalotetracycline are hydrogenated to the corresponding lla-dehalo products employinga palladium catalyst, such as palladium supported on barium sulfate, ruthenium,

osmium, rhodium, iridium and platinum in solvents such as the lower alkanols, dioxane, tetrahydrofuran, diglyme and monoglyme.

v 13- Example X lla-DEHALOGENATION Equivalent amounts of lla-halotetracycline,.sodium iodide and powdered zinc metal are refluxed in acetone for 30 minutes. The reaction mixture is cooled, filtered and concentrated under reduced pressure to obtain the lla-dehalotetracycline compound.

Employing this procedure, the above described 11ahalotetracyclines are converted to the corresponding lladehalo compounds. Similar results are obtained when .butauone and/or pentanone are used in lieu of acetone.

Example XI 7,9-DIBROMO-11a-FLUORO-6-DEOXY-6-DEMETHYL%- DESDIMETHYLAMINOTETRACYCLINE A mixture of 2 g. of lla-fluoro-6-deoxy-6-demethyl-4- desdimethylarninotetracycline and 2 g. of N-bromosuccinimide in 60 ml. of acetic acid is allowed to stand at room temperature. The product crystallizes directly from the mixture within one hour and is collected by filtration.

This product is also obtained from the corresponding 7-brorno-l la-fiuorotetracycline compound by this procedure.

Example XII 7,9-DIBROMO-6-DEOXY G-DEMETHYLA-DESDIMETHYL- AMINOTETR ACYCLINE The product of Example XI (25 mg.) is dissolved in 2 ml. of acetic acid and 25 mg. of powdered zinc is added to the mixture. The mixture is allowed to stand at room temperature for 15 minutes after which it is diluted with acetone, filtered and the filtrate freeze-dried to obtain the product.

Example XIII 7,9,11a-TRIBROMO-6-DEOXY-6-DE METHYL-4-DIDSDI METHYLAMINOTETRACYCLINE To a mixture of 2. g. of 6-deoxy6-demethyl-4-desdimethylaminotetracycline in 30 ml. of'acetic acid is added drop- Wise a solution of 4 g. of N-brornosuccinimide in 30 ml.

of a'cetic acid. The mixture is allowed to stand for 48 hours at room temperature and the product is then precipitated by water addition.

This product is also obtained by 7 corresponding lla-bromo compound and 7,1l'a-dibromo agent.

Example XVI 7,9,11a-TRICHLORO-G-DEOXY-G-DEMEIHYL--DESDI- METHYLAMINO'IETRACYCLINE This product is obtained by thepro'cedure of Example XIII employing N-chlorosuccinimide as halogenating "agent. I

7 Example XVII V I 7 ,9-DIBROMO-11a-CHLORO-G-DEOXY GDEMETHYL-4- DESDIMETHYLAMINOTETRACYOLINE. Two grams of lla-chloro-6-deoxy-6-demethyl-4 desdimethylaminotetracycline is dissolved in 10 ml. of acetic .acid containing 1.6 g. of bromine. The mixture is allowed to stand for 36 hours after which it is diluted with water and the product collected by filtration.

the bromination of the i The product is converted to 7,9-dibromo-6-deoxy-6-demethyl-4-desdimethylaminotetracycline by the procedure of Example XII. 1

Example XVIII T-BROMO-1la-FLUOR0-6-DEOXY-6-DEMETHYL-4-DE SDI- METHYLAMINOTETRACYCLINE cycline.

Example XIX 7,Q-DIBROMO-1ia-FLUORO-6-DEOXY-6-DEMETHYL-4- DI] SDIMEIHYLAMINOTETRACYCLINE To a solution of 2.5 g. of l'la-fluoro-6-deoxy-6-demethyl-4-desdimethylaminotctracycline in 25 ml. of trifiuoracetic acid is slowly added 10 ml. of a solution of bromine in acetic acid (1.6 g. of bromine). No precipitate forms. The mixture is heated on the steam bath for 30 minutes and then diluted with water to obtain the product.

On treatment with zinc and acetic acid, this product yields7,9 dibromo 6 deoxy-6-demethyl-4-desdimethylaminotetracycline.

' Example XX 7-BROMO-9-CHLOR0 11a-FLUOROiS-DEOXY-G-DEMETHYL- 4-DESDIMETHYLAMINOTETRACYCLINE The product of Example XVIII, 2.0 g., is dissolved in acetic acid and 0.8 g. of N-chlorosuccinimide in 30 ml. of acetic acid is added to the mixture. The mixture is allowed to stand for 24 hours and the product is then precipitated by water addition. The mixtureis filtered and the product washed and dried.

' Example XXI Employing the procedures of Examples XI to XIQthe following halodesdimethylaminotetracyclines are prepared: 7,9-dich1oro-1-1a-fluoro-6-deoxy 4 desdimethylaminotetracycline 7,9-dichloro-6-deoxy-4-desdimethylaminotetracycline 7,9-diiodo-6-deoxy-4-desdimethylaminotetracycline 7,9-dibrorno-6-deoxy4-desdimethylaminotetracycline 7,9, 1 1a-trichloro-6-deoxy-4-desdimethylaminotetracycline 7-fl uor o-9,-l 1a-dibromo-6-deoxy-4-desdimethylaminotetracycline V I 7-chloro-6-deoxy-6-demethyl 4 desdimethylaminotetra- V cycline p 7,9-dibromo-6-deoxy 4 desdimethylamino 5 --oxytetracycline I I 7,9-diiodo-1la-fluoro-6-deoxy-6-demethyl-4 desdimethylaminotetracycline 7,9-diiodo 6-deoxy-6-demethyl-4 desdimethylaminotetracycline Example-XXII '"z Bleoiuo a-DE10XY-6-DEMETHYLTETRACYc INEi To 1 g. of -7,lla dibromo-6 demethyl-6-deoxytetra- .cycline hydrobromide in' 20 mlof water is added with stirring 320 mg. of potassium sulfite dissolved in 5 ml. water. After stirring for 30 minutes at room temperature, filtration of the reaction mixture yields 650 mg. of

the product. p

7 Example XXIII 7-CHLORO-G-DEMETHYL-G-DEOXYTETRACYCLINE To a solution of 520 mg. of 7,11a-dichloro-6-deoxy-6- action mixture gave 430 mg. of 7-chloro-6-demethyl-6 deoxytetracycline.

' Example XXIV The hydrochloride of 7,1"1a-dichloro-6-deoxy-6-demeth-.

yltetracycline is prepared by dissolving the tetracycline compound in methanol containing an equivalent amount of hydrogen'chloride. The hydrochloride salt is then obtained by concentration of the reaction mixture.

ln this fashion, othermineral acid salts ofthe present new compounds are prepared with such acids as hydrobromic, sulfuric, hydriodic, phosphoric, and, hydrofluoric acids. r

' Example XXV The sodium salt of 7 ,11a-dichloro-6-deoxy-G-demethyltetracycline is prepared by dissolving the tetracycline compound in aqueous solution containing an equivalent amount of-sodium hydroxide. Concentration of 'the resulting solution yields the sodium salt.

Similarly, other alkali and alkaline earth metal salts of the present new compounds are prepared using the following salts: potassium, carbonate, lithium carbonate,

barium hydroxide, calcium hydroxide, strontium carbonate, magnesium hydroxide.

Example XXVI A suspension of llachloro-6-deoxy-6-demethyltetra- -Water, distilled, to make 1 liter.

To this suspension, various sweetening and flavoring agents, as-well-as acceptable colors, .may be added by choice. The suspension contains approximately 25 .mg. of antibiotic activity per milliliter.

Example XXVI] A solution of 11a-chloro-6-deoxy-6-demethyltetracycline is prepared with the following composition:

Antibiotic g 30.22 Magnesium chloride'hexahydrate g 12.36 Monoethanolamine -ml 8.85 Propylene glycol g 376 Water ml '94 The solution has a concentration of 50 mg./ml. and is suitable for parenteral, and especially for intramuscular administration.

Example XXVIII A' tablet base is prepared by blending the-following ingredients in the proportion by Weight indicated.

Grams Sucrose, U.S.P 80.3 Tapioca-star h 13.2 Magnesium stearate 6.5

7 into thisbas e there is blended suflicient lla-chloro-fi deoxy-6-demethyltetracycline to provide tablets containing 25, 100 and 250 mg. of active ingredient.

. Example XXIX V A blend is prepared containing the following ingredients:

. s Grams Calcium carbonate, U.S.P... 17.6

-Di calcium-phosphate 18.8

1'5 Magnesium trisilicate, U.S.P. 5.2 Lactose, U.S.P 5.2 Potato starch--- 5.2 Magnesium stearate A 0.8 Magnesium stearate B 0.32

To this blend is added sufiicient 11a-chloro-6-deoxy-6- demethyltetracycline. to provide capsules containing 25, 100 and 250 mg. of active ingredient.

10 Example XXX One thousand grams of 11a-chloro-6-deoxy-6-demethyltetracycline are intimately mixed and ground with 2500 grams of ascorbic acid. The ground, dry mixture is filled into vials, sterilized with ethylene oxide and the 15 vials sterilely stoppered. For intravenous administration sufficient water is added to the vials to form a solution containing 10 mg. of active ingredient per milliliter.

The procedures of Examples XXVI-XXX is repeated with other lla-halotetracyclines described'in the preceding examples to form corresponding dosage forms.

This application is a continuation-in-part of application Serial No. 847,866, filed October 22, 1959, now abandoned.

What is claimed-is:

1. A compound selected from the group consisting of compounds of the formula:

R R1 R:

-CONH 2 I H X H 1 on 0 o o wherein:

R is selected from the group consisting of H and CH R is selected from the group consisting of H and, when R is CH OH;

R is selected from the group consisting of hydrogen and -N(CH and X is halogen;

and the mineral acid salts thereof and'alkali and alkaline earth metal salts thereof.

2. A compound selectedfrom the group consisting of compounds of :the formulae:

I X H I on 0 o on Y t r CONH2 Yx n 1 OH 0 o 0 wherein:

R is selected from the group consisting of H and CH R is selected from the group consisting of H and,

when R is CH OH;

R is selected from the group consisting of H and Xand Y are halogen; and

B is selected from the group consisting of chloro,

bromo and iodo;

and the mineral-acid salts thereof and alkali and alkaline earth metal salts thereof.

3. 11a-chloro-6-deoxy-6-demethyltetracycline. 4. 11a bromo 6-deoxy-6-demethyltetracycline. 5. 11a-fluoro-6-deoxytetracycline. 6. l1a-bromo-6-deoxy-S-oxytetracycline. 7. 7,9,11a tribromo-6-deoxy 6 demethyl-4-desdimethylaminotetracycline.

methylaminotetracycline. I

9. 7,9-dibromo-11a-fluoro-6-deoxy-4-desdimethylaminotetracycline.

10. 7-bromo-11a-fluoro-6-deoxy-6-demethyl 4 desdimethylaminotetracycline.

.11. 7,9 diiodo-l1a fiuoro-6-deoxy-6-demethyl-4-desdi- B C ONH,

in which:

R is selected from the group consisting of H and CH R is selected from the group consisting of H and, when R is CH OH; Y is halogen; and B is selected from. the group consisting of bromo,

chloro, and iodo;

and alkali and alkaline earth metal salts thereof.

18. The process for the lla-dehalogenation of a 6 deoxy-l1a-halotetracycline selected from the group consisting of Y R R1 @/\A I B l Y R R1 2 and mineral acid salts thereof wherein R is selected from the group consisting of H and CH B is selected from the group consisting of chloro,

bromo and iodo;

R is selected from the group consisting of H and,

when R is CH 0H;

R is selected from the group consisting of H and X and Y are each selected from the group consisting of chloro, fluoro and bromo;

which comprises treating said 6-deoxy-11a-halotetracycline with at least one equivalent of each of zinc and sodium iodide in a reaction inert solvent.

19. The process for the lla-dehalogenation of a 6- deoxy-lla-halotetracycline selected from the group consisting of Y Ill R;

/\A OH B \V/ CONH:

H X." l n o o 0 Y R R1 B2 A/\ i 03 \V/ CONH: 1] KY 1 1 H o o o and mineral acid salts ther'eof wherein R is selected from the group consisting of H and CH B is selected from the group consisting of chloro,

hromo and iodo;

R is selected from the group consisting of H and,

when R is CH OH;

R is selected from the group consisting of H and X and Y are each selected from the group consisting of chloro, fluoro and bromo;

which comprises treating said G-deoxy-l la-halotetracycline with hydrogen in the presence of a noble metal catalyst at a pressure of from about one to about three atmospheres and a temperature of up to about 50 C. in a reaction-inert solvent until one equivalent of hydrogen is taken up.

20. The process for the lla-dehalogenation of a.6 deoxy-lla-halotetracycline selected from the group consisting of I .011 B CONE \I/XY l H O O 0 Y R R1 R:

I OH Y CONH2 1 Y OH O O and mineral acid salts thereof wherein R is selected from the group consisting of H and CH B is selected from the group consisting of chloro,

hrorno and iodo;

R is selected from the group consisting of H and when R is CH OH;

R is selected from the group consisting of H and X and Y are each selected from the group consisting of chloro, fluoro and bromo;

which comprises treating said 6-deoxy-lla-halotetracycline with zinc metal in acetic acid.

21. The process for the lla-dehalogenation of a 6- deoxy-lla-halotetracycline, selected from the group con- R is selected from the group consisting of H and,

sisting of when R is CH OH; R R1 v R is selected from the group consisting of H -and H 5 V X and Y are each selected from the group consisting of chloro, fluoi'o and bromo;

;which comprises treating said 6-deoxy-l1a-halotetra- H X cycline with an aqueous solution of an alkali metal hydro- 0 0 Y O sulfite.

a 10 i 7. 0H

References Cited inthe file of this patent Y 7 UNITED STATES PATENTS o 2,736,725 Ritter 1- Feb. 28, 1956 i CONE: FOREIGN PATENTS Y H 167,948 Australia Mar. 18, 1954 H o 0 0 167,750 Australia May 6, 1954 OH 215,191 Australia Aug. 30, 1956 785,047 Great Britain Oct. 23, 1957 and mineral acid salts thereof wherein R is selected from the group consisting of H and CH B is selected fromthe group consisting of chloro,

bromo and iodo; 7

OTHER REFERENCES Stephens etal.: J. Amen Chem. Soc, vol. 80, pages 53245325 (1958). v 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF THE FORMULA:
 2. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF THE FORMULAE: 